Hi tech seatbelts have built in airbags

By: Luigi Fraschini

Date: Monday, 14. December 2009

Air bags and seat belts are two safety innovations that have saved thousands of lives. So, why not combine the ideas? That's the thinking behind the world's first automotive inflatable seat belts. The innovation, to be introduced by Ford Motor Co., mixes attributes of traditional seat belts and air bags to provide an added level of crash safety protection for rear-seat occupants.

The new restraint system is designed to help reduce head, neck and chest injuries for rear-seat passengers -- often children and older passengers, who can be more vulnerable to such injuries. The inflatable rear seat belts will debut on the next-generation Ford Explorer, which goes into production next year. Over time, Ford plans to offer the technology in vehicles globally.

'Ford's rear inflatable seat belt technology will enhance safety for rear-seat passengers of all ages, especially for young children who are more vulnerable in crashes,' said Sue Cischke, Ford group vice president of sustainability, environmental and safety engineering. 'This is another unique family technology that builds on our safety leadership, including the most top safety ratings of any automaker.'

But how do they feel?

In everyday use, the inflatable belts operate like conventional seat belts and are compatible with safety car seats for infant and children. Made possible by advances in air bag inflation and seat belt construction methods, they are designed to deploy over a vehicle occupant's torso and shoulder in 40 milliseconds during a crash. In a frontal or side crash, the increased diameter of each inflatable belt holds the occupant in the appropriate seating position more effectively, helping reduce the risk of injury. The use of cold compressed gas instead of a heat-generating chemical reaction, which is typical of traditional air bag systems, means the inflated belts feel no warmer on the wearer's body than the ambient temperature.

One might suspect the inflatable belts would be bulky and uncomfortable, but in Ford's research, more than 90 percent of those who tested the inflatable seat belts found them similar to or more comfortable than a conventional belt thanks to their padding and softness. That comfort factor could help improve the 61 percent rear belt usage rate in the U.S. -- versus 82 percent usage by front-seat passengers, according to National Highway Traffic Safety Administration data.

'Ford is pioneering inflatable seat belt technology to help enhance crash safety protection while encouraging more people to buckle up with a more comfortable belt,' said Paul Mascarenas, Ford vice president of engineering for global product development.

The wearer has to do nothing beyond buckling up in the first place. When a crash occurs, vehicle safety sensors determine the severity of the collision in the blink of an eye and deploy the inflatable belts air bags. Each belt's tubular air bag inflates with cold compressed gas, which flows through a specially designed buckle from a cylinder housed below the seat. The inflatable belt's accordion-folded bag breaks through the belt fabric as it fills with air, expanding sideways across the occupant's body in about the same amount of time it takes a car traveling at highway speed to cover a yard of distance.

'It's a very simple and logical system, but it required extensive trial and error and testing over several years to prove out the technology and ensure precise reliable performance in a crash situation,' said Srini Sundararajan, safety technical leader for Ford research and advance engineering.

---Luigi Fraschini, Cleveland-based contributing editor of Driving Today, writes frequently about safety advancements.

Related Links:

• Drivers.com's articles and links on Safety Restraints
• Drivers.com's articles and links on Airbags

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